Within the framework of an experimental longline fishing campaign at sea in the Bay of Biscay, a first evaluation of the adequacy of the bluefin tuna catches with the requirements of the Japanese market for the preparation of sashimi has been carried out. The criteria to define a higher quality tuna are: a high level of freshness, signs of a fast bleeding of tuna after the landing, the absence of "yake" or burn of the flesh due to lactic acid formation, the absence or a very low content in histamine and a high fat content. The tunas caught during the seven trips were all classified as Extra quality fishes in the auction. Very low level of histamine was detected (15 mg/kg). The analyses done on six fishes of different sizes in several points (four per fish) confirmed the distinction of the flesh in two classes. The "toro" is rich in fat (minimum 15% from 40 kg) and the "akami" is clearly leaner (below 7% on average); a rapid increase of the fat content linked to the weight has been observed for the fishes of more than 50 kg. In the perspective of a development of the catches for the sashimi market, the handling of the product onboard could be appreciably improved.

Fish freshness of eight marine species was evaluated by two different methods: the K-value measured by a colorimetric strip-test (Transia Fresh Tester (R)) reflecting the ATP degradation (Adenosine triphosphate), and the sensory analysis assessed according to the EU scheme. The regression analysis suggests different linear and logarithmic models according to the fish species. The strongest correlations are obtained for tunas, mackerel, anchovy, black bream and sea bass (0,81 < r(2) < 0,93), and the weakest ones for sole (r(2) = 0,69) and hake (r(2) = 0,46). Models have been used to calculate the prediction interval at 95% of the freshness degree according to the K values.